Never trust the network in any circumstance. If you start from that basis then life becomes easier.
Google has a good approach to this: https://cloud.google.com/beyondcorp
EDIT:
I’d like to add a tangential rant about companies still using shit like IP AllowLists and VPNs. They’re just implementing eggshell security.
They’re not more effective. They might assist with speed of absorption but that’s it.